I've been using it for years now and it's great. Not only for Youtube videos, but also for a lot of other video hosters, up to and including TV stations such as the German ZDF or the French Arte. To fully use its features you should install ffmpeg though. Youtube-dl will automatically use it if it's in the PATH, and then can download Youtube videos with higher frame rates and resolutions (they store video and audio i…
I like this command to extract audio from youtube videos: youtube-dl --extract-audio --audio-format mp3
[1] A bit of self-promotion here, if you are interested this is my soundcloud playlist https://soundcloud.com/melicerte/sets/extraits-de-vieux-film...